The invention relates to an analysis device for analyzing samples, in particular for medical applications. The samples are preferably body liquids, as e.g. blood or urine. The target of the analysis is to detect the existence, or the concentration, respectively, of a component (analyte) of the sample.
In such analysis devices, the procedures necessary for the analysis are performed automatically. To this end, samples and reagent components are dosed into containers (reaction vessels), mixed and incubated for determined reaction times. The reaction of the sample with the reagents leads to a measurable change which is characteristic for the analysis, and is measured and evaluated for the determination of the analysis result. Numerous different analysis devices are known. These differ widely with respect to reaction principles (e.g. classical clinical chemistry; chemoimmunology, DNA analytics), and with respect to the measured variable characteristic for the analysis (e.g. photochemically measurable color changes, turbidimetry, electrochemical measurement) as well as with respect to the design of the apparatus. These different methods are known and are not the subject of the present invention.
Many analysis devices have in common that they comprise a plurality of (stationary or movable) stations, where partial steps of the procedure necessary for the analysis are performed. Most of these stations serve, in any form, for handling liquids; thus, they are generally designated liquid handling (LH) stations. Typical examples are dosing stations, where a liquid (reagent or sample) is dosed into a reaction vessel by means of thin tubes (dosing needles), or mixing stations, where liquids are mixed with other liquids and/or solid components (e.g. suspended pellets as carriers for fixed immune reagents, so-called beads) by means of a stirrer immerged into the reaction vessel. Measurement stations, too, can be regarded as LH stations, as far as the measurement requires a liquid handling step, as e.g. the filling and emptying of a measuring cell.
The LH stations of such analysis devices typically include one or more washing stations, where a processing tool, e.g. a dosing needle or a stirrer, is cleaned. A very good cleaning of the tools which are submerged into liquids of different composition, is very important with respect to the exactness of the analysis, as impurities lead to a transfer of one liquid to another (passive dispersal). In order to obtain a cleaning as effective as possible, different designs of washing stations were proposed. An example of washing stations which can be applied very advantageously with the present invention, is described in international patent application WO 97/35173.
At a part of the LH stations of common analysis devices there is a production of liquid waste which must be disposed of. In case of washing stations, the liquid waste consists, in particular, of the washing liquids used there, with the washed-off residues of reagents and/or samples. At other LH stations there may be produced liquid waste, too, e.g. a reaction mixture at the measuring station which is not needed any longer after the termination of the measurement. At other processing stations, e.g., dosing surpluses may be produced, being evacuated at an overflow of the reaction vessel. All LH stations producing liquid waste are designated here as liquid waste sources.
Typically, the liquid waste is disposed of by guiding it into a liquid waste container via a conducting system. For some analysis devices, the liquid waste container is arranged in such a way below the liquid waste sources, that the liquid waste drains by gravity only. However, this requires a relatively high design shape of the device as well as liquid waste tubes with large diameter and sufficient gradient. Furthermore, the washing stations of such devices must be designed in a way that the washing liquid drains spontaneously. In order to avoid these problems, pumps are used which evacuate the liquid waste at the liquid waste sources and transport it to the liquid waste container.
Generally, the liquid waste produced at the liquid waste sources of analysis devices does not only consist of liquids, but contains portions of air, which vary with respect to their quantity during the procedure performed by the analysis device. Thus, the term xe2x80x9cliquid wastexe2x80x9d must be understood in a way that this is a kind of waste which can be pumped as a liquid, but may, apart from the liquid components, contain air (or other gases) as well as dispersed solid matter. As far as the liquid portion of the waste is referred to here, this is the average volume ratio of liquid in the tubes leading from the corresponding liquid waste source to the liquid waste container, during the processing of the device.
The liquid waste of analysis devices usually contains components (in particular detergents contained in washing liquids and in reagents) which produce foam in the liquid waste container. This leads to severe disadvantages. The foam rapidly fills the liquid waste container, making it necessary to empty it in order to avoid contamination. Furthermore, the foam interferes with the liquid level detection most liquid waste containers are equipped with.
For decreasing the foam production in the liquid waste container, it is possible to add chemical substances (antifoam) to the liquid waste, which impede the foam production. However, this requires additional handling steps and/or special constructive measures on the device for the dosing of antifoam compounds. Furthermore, the chemical foam elimination causes additional cost and, possibly, additional problems with the environmentally appropriate disposal if the liquid waste from the liquid waste container.
Another possibility for reducing the problems caused by foam production is the use of particularly big liquid waste containers. However, this is contrary to the required space-saving design of analysis devices.
On this basis, the invention addresses the problem to reduce the foam production in the liquid waste containers of analysis devices with as little expense as possible, with respect to the design of the device as well as with respect to the handling of the device.
This problem is solved by an analysis device for analyzing samples, in particular body liquids, with respect to components contained therein, with a plurality of liquid handling (LH) stations, which include processing stations. At these processing stations, processing steps are performed by means of processing tools as e.g. a dosing needle or a stirrer, at liquids contained in containers. At at least a part of the LH station, liquid waste is produced, thus forming liquid waste sources. The liquid waste produced there, containing different portions of air, is evacuated by means of at least one pump, from the liquid waste sources, via a liquid waste conducting system, to a liquid waste container. The liquid waste conducting system has at least two separate tubes leading into the liquid waste container; a plurality of liquid waste sources is connected to at least one of these tubes. From these sources, there are separate tubes acting as secondary lines and guiding towards a line junction. From this line junction, a common tube leads as primary line into the liquid waste container. The secondary lines are grouped together in such a way that in one of the at least two lines guiding into the liquid waste container, there is liquid waste with a higher portion of air, and in another of the at least two lines guiding into the liquid waste container, there is liquid waste with a lower portion of air.
Analysis devices with conducting systems which comprise a plurality of separate liquid waste lines conducted to the liquid waste container, are known in different designs, e.g. from U.S. Pat. No. 5,820,824, EP 0825446 A2 and EP 0918221 A2.
In the scope of this invention it was determined that the foam production can be reduced dramatically by combining the liquid waste flow from the different liquid waste sources depending on the average amount of air transported in the tubes of the liquid waste conducting system, so that at least two partial flows are guided through separate lines and are pumped completely separate into the liquid waste container, whereas one of these partial flows contains a relatively high air proportion and the other partial flow contains a relatively low air proportion.
The liquid waste sources are grouped in a way that a plurality of liquid waste sources are connected to at least one of the separate lines leading into the liquid waste container. For this purpose, separate tube sections (xe2x80x9csecondary linesxe2x80x9d) exist, leading from the liquid waste sources to at least one line junction. After the junction of all partial flows of a group, the resulting liquid waste flows, in a common line section (xe2x80x9cprimary linexe2x80x9d of the group) to the liquid waste container. According to the number of liquid waste sources, different combinations are possible.
The liquid waste source groups, the wastes of which are grouped and commonly lead to the liquid waste container, are divided in a way that the resulting liquid proportions of the two lines leading into the liquid waste container, significantly differ from each other (preferably at least by the factor 1,5). Preferably, there is a first group consisting of liquid waste source with a relatively high air proportion, and a second group consisting of liquid waste sources with a relatively low air proportion. xe2x80x9cRelatively highxe2x80x9d and xe2x80x9crelatively lowxe2x80x9d has to be understood in a way that in the group with the higher air proportion there is no liquid waste source with a lower air proportion than the highest air proportion of the other group. With other words, there is a limit value for the average air proportion in a way that the liquid waste sources of the first group are above, and the liquid waste sources of the second group are below this limit value.
However, the designation xe2x80x9crelatively low air proportionxe2x80x9d must not be understood in a way that the air volume flow is lower than the water volume flow. Due to the design is and the operation of common LH stations, and, in particular, common washing stations, even for a liquid waste source with xe2x80x9crelatively lowxe2x80x9d air proportion, during the major part of the overall operating time, only or preponderantly air is evacuated from the liquid waste source. In the scope of the experimental evaluation of the invention, even liquid waste sources with an average air volume proportion of more than 80% (e.g. an average of 5 seconds of liquid transport per minute) were assigned to the group with a xe2x80x9crelatively lowxe2x80x9d air proportion.
A high air volume flow, as compared to the water volume flow, results, in particular, in analysis devices where the liquid waste of a plurality of liquid waste sources is evacuated with a common, continuously driven pump. The application of a common pump results in substantial savings of cost, constructive volume and weight, as compared to individually controlled evacuation pumps assigned to separated liquid waste sources. On the other hand, these designs have particular problems with foam production.
If there are four or more liquid waste sources, it is in principle possible to lead more than two primary lines to the liquid waste container. According to the experimental evaluation of the invention, this is not necessary in the normal case. It is enough to have two separate liquid waste lines, differing as described with respect to the transported air proportion, leading into the liquid waste container.